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      <title>消息等待机制实现 - 交互式测验</title>
      <style>
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          margin: 0;
          padding: 20px;
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        .quiz-header {
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        .quiz-header h1 {
          margin: 0;
          font-size: 24px;
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        .quiz-header p {
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            font-size: 14px;
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        .quiz-body {
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        .progress-bar {
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            margin-bottom: 20px;
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        #progress-indicator {
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        #question-container {
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        #question-text {
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          font-weight: 500;
          line-height: 1.6;
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        .options-list {
          list-style: none;
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          margin: 0;
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        .option-item {
          background-color: #f8f9fa;
          border: 1px solid #dee2e6;
          border-radius: 8px;
          padding: 15px;
          margin-bottom: 12px;
          cursor: pointer;
          transition: background-color 0.2s ease, border-color 0.2s ease;
        }

        .option-item:hover {
          background-color: #e9ecef;
        }
        
        .option-item.selected {
            background-color: #d1e7fd;
            border-color: #4a90e2;
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        .quiz-footer {
          padding: 20px 30px;
          display: flex;
          justify-content: space-between; /* 将按钮分布在两侧 */
          align-items: center;
          min-height: 65px; /* Reserve space */
        }

        .nav-btn {
          background-color: #4a90e2;
          color: white;
          border: none;
          border-radius: 8px;
          padding: 10px 20px;
          font-size: 16px;
          font-weight: 500;
          cursor: pointer;
          transition: background-color 0.2s ease, transform 0.2s ease;
          box-shadow: 0 4px 12px rgba(0,0,0,0.15);
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        #next-btn {
            background-color: #28a745;
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        .nav-btn:hover {
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        .nav-btn:disabled {
            background-color: #a0c3e8;
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            opacity: 0.7;
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        #result-container {
            border-top: 1px solid #eee;
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        .result-box {
            border-radius: 8px;
            padding: 20px;
            margin-top: 20px;
        }
        
        .result-box.correct {
            background-color: #d4edda;
            border: 1px solid #c3e6cb;
            color: #155724;
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        .result-box.incorrect {
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        .result-box h3 {
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        .source-text {
            font-style: italic;
            font-size: 14px;
            margin-top: 15px;
            color: #555;
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        .final-score-container {
            padding: 40px;
            text-align: center;
        }
        .final-score-container h2 {
            margin-top: 0;
            margin-bottom: 30px;
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        .score-summary {
            display: flex;
            justify-content: center;
            gap: 20px;
            margin-bottom: 40px;
            flex-wrap: wrap;
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        .score-card {
            background-color: #f8f9fa;
            border-radius: 12px;
            padding: 20px;
            width: 180px;
            box-shadow: 0 4px 12px rgba(0,0,0,0.05);
            border: 1px solid #e9ecef;
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        .score-card h3 {
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            font-size: 16px;
            font-weight: 500;
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            font-size: 28px;
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            font-size: 16px;
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        .score-details td {
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        .score-details td:last-child {
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            font-size: 15px;
            line-height: 1.6;
            display: none; /* 默认隐藏 */
        }
      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>消息等待机制实现 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "根据文档，长轮询（Long Polling）与传统轮询（Polling）最本质的区别是什么？",
    "options": [
      "长轮询由服务端主动发起请求，而传统轮询由客户端发起。",
      "长轮询需要维护一个永久的TCP长连接，而传统轮询不需要。",
      "当服务端没有新数据时，长轮询会挂起请求并等待，而传统轮询会立即返回空结果。",
      "长轮询能够保证消息的绝对顺序，而传统轮询不能。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档明确指出，传统轮询无论服务端是否有数据都会立即响应。而长轮询的核心特点是，当服务端没有可用数据时，不会立即返回，而是保持连接（即挂起请求）一段时间，直到有新数据或超时。这大大减少了因空结果而产生的无效网络请求。",
    "source": "文档中「长轮询的基本概念」->「与传统轮询的区别」部分",
    "hint": "思考一下，在没有新消息的情况下，两种轮询方式的服务端响应行为有何不同？"
  },
  {
    "question": "在RocketMQ的实现中，哪个组件专门负责管理被挂起的消费者拉取请求？",
    "options": [
      "PullMessageProcessor",
      "DefaultMQPullConsumer",
      "PullRequestHoldService",
      "MessageStore"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档中提到，Broker端的 `PullRequestHoldService` 是专门用来处理挂起拉取请求的服务。它会维护一个请求映射表，并定期检查是否有新消息到达以唤醒对应的请求，同时也会处理请求超时，防止请求被无限期挂起。",
    "source": "文档中「RocketMQ中的长轮询实现」->「PullRequestHoldService」部分",
    "hint": "在Broker端，需要一个“管家”来存放和检查那些正在等待消息的请求。"
  },
  {
    "question": "在RocketMQ长轮询机制中，`brokerSuspendMaxTimeMillis` 这个关键参数的作用是什么？",
    "options": [
      "消费者在发起下一次拉取请求前的固定等待间隔。",
      "消费者客户端等待Broker响应的总超时时间。",
      "Broker端在没有新消息时，挂起一个拉取请求的最长时间。",
      "当拉取发生异常时，消费者延迟下一次拉取的时间。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "根据文档定义，`brokerSuspendMaxTimeMillis` 是Broker侧的配置，它决定了当没有新消息时，一个拉取请求可以在Broker端被挂起（hold）多久。默认值为15秒。与之对应的是`consumerTimeoutMillisWhenSuspend`，那是消费者侧的等待超时。",
    "source": "文档中「RocketMQ中的长轮询实现」->「关键参数」部分",
    "hint": "这个参数的命名中包含了 'broker' 和 'suspend'，暗示了它的作用域和行为。"
  },
  {
    "question": "长轮询机制为RocketMQ带来了多项优势，但不包括以下哪一项？",
    "options": [
      "通过减少无效请求来降低网络开销。",
      "在新消息到达时能立即响应，提高了实时性。",
      "完全取代了推送（Push）模式，成为唯一的消息获取方式。",
      "客户端主动拉取，避免了服务端推送可能出现的消息丢失问题，提高了可靠性。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "长轮询是一种“拉”模式的优化，它在实时性上接近“推”模式，但并未完全取代它。文档将长轮询描述为“一种介于传统轮询和推送模式之间的通信方式”，并分别与两者进行了对比。它是一种重要的核心机制，但并非唯一的消息获取方式。",
    "source": "文档中「长轮询的优势」及「长轮询的基本概念」部分",
    "hint": "长轮询是一种折衷和优化方案，思考它与推送模式的关系是替代还是共存？"
  },
  {
    "question": "在RocketMQ的拉取模式中，如果一个消费场景要求高吞吐量，并且消费者不希望处理消息的线程被长时间阻塞，应该优先选择哪种拉取方式？",
    "options": [
      "同步拉取 (Synchronous Pull)",
      "异步拉取 (Asynchronous Pull)",
      "基于时间的拉取 (Time-based Pull)",
      "过滤拉取 (Filter-based Pull)"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档明确指出，异步拉取“适用于高吞吐量场景”。因为它发送请求后不阻塞当前线程，而是通过回调函数来处理结果。这使得消费者可以继续执行其他任务或发起更多请求，从而提高并发度和整体吞吐量。同步拉取则会阻塞线程，不适合此场景。",
    "source": "文档中「消息拉取的等待策略」->「拉取模式分类」->「异步拉取」部分",
    "hint": "哪个模式允许你在等待消息响应的同时，不阻塞当前的工作线程？"
  },
  {
    "question": "当消费者调用`pull`方法后，返回的`PullResult`状态为`NO_NEW_MSG`时，根据文档中的示例代码，推荐的下一步操作是什么？",
    "options": [
      "立即重置消费偏移量（offset）。",
      "更新消费偏移量到`pullResult.getNextBeginOffset()`。",
      "等待一个预设的间隔时间（pullInterval）后再发起下一次拉取。",
      "立即发起同一个偏移量（offset）的拉取请求。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档中的示例代码清晰地展示了对不同`PullStatus`的处理逻辑。对于`NO_NEW_MSG`，代码块中的注释是“没有新消息，等待一段时间再拉取”，并执行了`Thread.sleep(pullInterval)`。这是一种避免无效空轮询的退避策略。",
    "source": "文档中「消息拉取的等待策略」->「等待策略实现」->「基于偏移量的等待」的代码示例部分",
    "hint": "在代码示例的 `switch` 语句中，找到 `case NO_NEW_MSG:` 分支，看看它是如何处理的。"
  },
  {
    "question": "在什么场景下，使用“基于时间的等待”策略（即从指定时间点开始消费）是特别合适的？",
    "options": [
      "需要对消息内容进行复杂筛选的场景。",
      "首次启动消费者，希望从队列头部开始消费的场景。",
      "需要对历史消息进行回溯或重新消费的场景。",
      "对消息处理实时性要求达到毫秒级的场景。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档中明确提到，基于时间的等待策略“适用于消息回溯或重新消费场景”。例如，当业务逻辑变更或出现故障修复后，需要重新处理过去一小时内的所有消息，此时就可以指定一个一小时前的时间戳来开始消费。",
    "source": "文档中「消息拉取的等待策略」->「等待策略实现」->「基于时间的等待」部分",
    "hint": "这个策略允许你“穿越”回过去某个时间点，这通常是为了什么目的？"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
        // 存储每个问题的回答状态
        const userAnswers = new Array(quizData.length).fill(null); 

        const questionTextEl = document.getElementById('question-text');
        const optionsListEl = document.getElementById('options-list');
        const resultContainerEl = document.getElementById('result-container');
        const quizContentEl = document.getElementById('quiz-content');
        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

        function loadQuestion() {
          resultContainerEl.innerHTML = '';
          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
          if (currentQuestionIndex >= quizData.length) {
            showFinalScore();
            return;
          }

          updateProgress();

          const currentQuestion = quizData[currentQuestionIndex];
          questionTextEl.textContent = `(${currentQuestionIndex + 1}/${quizData.length}) ${currentQuestion.question}`;
          
          currentQuestion.options.forEach((optionText, index) => {
            const li = document.createElement('li');
            li.className = 'option-item';
            li.textContent = optionText;
            li.dataset.index = index; // Store index in a data attribute
            // 如果这道题已经回答过，恢复状态
            if (userAnswers[currentQuestionIndex] !== null) {
                if (index === userAnswers[currentQuestionIndex]) {
                    li.classList.add('selected');
                }
            }
            optionsListEl.appendChild(li);
          });

          // 如果已经回答过，直接显示结果
          if (userAnswers[currentQuestionIndex] !== null) {
              const isCorrect = userAnswers[currentQuestionIndex] === currentQuestion.correctAnswerIndex;
              showResult(isCorrect, currentQuestion);
          }
          
          updateNavigationButtons();
          updateProgress();
        }

        function selectOption(optionIndex) {
            userAnswers[currentQuestionIndex] = optionIndex;
            const currentQuestion = quizData[currentQuestionIndex];
            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
            score = userAnswers.reduce((acc, answer, index) => {
                return answer === quizData[index].correctAnswerIndex ? acc + 1 : acc;
            }, 0);

            showResult(isCorrect, currentQuestion);
            updateNavigationButtons();
        }
        
        function updateProgress() {
            const answeredQuestions = userAnswers.filter(answer => answer !== null).length;
            const progressPercentage = (answeredQuestions / quizData.length) * 100;
            progressIndicatorEl.style.width = `${progressPercentage}%`;
        }
        
        function updateNavigationButtons() {
            prevBtn.style.display = 'block';
            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
            // 如果当前问题没有提示，则禁用提示按钮并隐藏提示内容
            if (!quizData[currentQuestionIndex].hint) {
                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
            } else {
                hintBtn.disabled = false;
            }
        }

        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

            // 禁用所有选项的点击事件，并高亮正确/错误答案
            Array.from(optionsListEl.children).forEach((child, index) => {
                child.style.pointerEvents = 'none';
                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
                }
            });
        }

        function goToNextQuestion() {
            if (currentQuestionIndex < quizData.length - 1) {
                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
            }
        }

        function goToPreviousQuestion() {
            if (currentQuestionIndex > 0) {
                currentQuestionIndex--;
                loadQuestion();
            }
        }
        
        function showHint() {
            const currentQuestion = quizData[currentQuestionIndex];
            if (currentQuestion.hint) {
                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  